Light emitting diodes may be used as white light sources in various applications, such as flash sources for cellular telephone cameras and filament lamps. Such LEDs may be referred to herein as white LEDs.
White LEDs may appear to emit white light from the perspective of the viewer when the LEDs are in an on state. However, they may actually be made up of light emitting semiconductor structures that emit non-white light, as well as wavelength converting structures that make the non-white light appear white to the viewer. For example, a white LED may be formed from a blue light emitting semiconductor structure covered by a yellow emitting phosphor layer. Photons of blue light emitted by the light emitting semiconductor structure may either pass through the yellow emitting phosphor layer as blue photons or may be converted into yellow photons by the yellow emitting phosphor layer. The blue and yellow photons that are ultimately emitted out of the LED combine to make the light emitted from the LED appear white to the viewer.
LEDs can also be used across a range of dimtone settings. However, an LED that appears to emit cooler light at a high dimtone setting for example, may also appear to emit cooler at a low dimtone setting. Likewise, an LED that appears to emit warmer light at a low dimtone setting for example, may also appear to emit warmer at a high dimtone setting.